The western part of Massachusetts, considered anything past Worchester for the most part. Includes some small towns, but mostly trees and cows. The reaction to anyone from the good part of Massachusetts when asked if they have heard of a town in Western Mass is "Where's that?"

"No way, you're from Massachusetts? I was born in Leyden!"
"... Where's that? Western Mass??"

Short for Western Massachusetts. Western Mass is, as the name implies, the western half of the Commonwealth of Massachusetts and is made up of four counties, Berkshire, Franklin, Hampden, and Hampshire. Often called Massachusetts' "better half" due to the fact that it offers the same charm as the eastern half of the state, with more natural scenery and less hussle and bussle.